Applied ergonomics
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Carrying a casualty on a stretcher is a critical task within military and emergency service occupations. This study evaluated the impact of manipulating carry speed and the object type in bilateral carries on the ability to predict performance and reflect the physical and physiological requirements of a unilateral stretcher carry. We demonstrated that three task-related predictive tests; a jerry can carry performed at 4.5 km h(-1)or 5.0 km h(-1) and a kettle-bell carry performed at 5.0 km h(-1) were strongly predictive of the physical and physiological demands of an individual participating as part of a four-person stretcher carry team. Therefore, bilateral predictive assessments have the utility for predicting the suitability of employees to effectively and safely conduct a four-person unilateral stretcher carry.
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Shorter, more frequent rosters, such as 6h-on/6h-off split shifts, may offer promise to sleep, subjective sleepiness and performance by limiting shift length and by offering opportunities for all workers to obtain some sleep across the biological night. However, there exists a paucity of studies that have examined these shifts using objective measures of sleep and performance. The present study examined neurobehavioural performance, sleepiness and sleep during 6h-on/6h-off split sleep schedules. ⋯ Overall, these results show that while there was not a cumulative cost to performance across days of splitting sleep, participants obtained less sleep and reported lowered alertness on shift days. Tests near the circadian nadir showed higher sleepiness and increased performance deficits. While this schedule did not produce cumulative impairment, the performance deficits witnessed during the biological night are still of operational concern for industry and workers alike.
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The study was done to identify affective and sensory responses observed as a result of hysteresis effects in transient thermal conditions consisting of warm-neutral and neutral - warm performed in a quasi-experiment setting. Air-conditioned building interiors in hot-humid areas have resulted in thermal discomfort and health risks for people moving into and out of buildings. Reports have shown that the instantaneous change in air temperature can cause abrupt thermoregulation responses. ⋯ However, TCV collected from warm-neutral (-0.24, ± 1.2) and neutral-warm (-0.72, ± 1.3) conditions revealed statistically significant mean differences (p < 0.05). Sensory and affective responses as a consequence of thermal transition after travel from warm-neutral-warm conditions did not replicate the hysteresis effects of brief, slightly cool, thermal sensations found in previous laboratory experiments. These findings also indicate that PMV is an acceptable alternative to predict thermal sensation immediately after a down-step thermal transition (≤ 1 min exposure duration) for people living in a hot-humid climate country.
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A significant portion of the population (25-50%) is known to develop acute low back pain (LBP) within a bout of prolonged sitting. Previous research has supported the use of frequent rest breaks, from seated office work, in order to reduce self-reported LBP, however, there is limited consensus about the recommended frequency and duration of rest breaks. This may be due to the limited consideration of individual differences in acute LBP development. ⋯ PD and NPD developed mental fatigue equally, with Conditions B and D helping to reduce fatigue. No differences in productivity were observed between conditions or groups and no main effects were observed for muscle activity, median power frequency or co-contraction. These data suggests that frequent, short, standing rest breaks may help to reduce symptoms of LBP, however they are only a temporary solution as PD still developed clinically important LBP, even with frequent rest breaks.
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This study compared the ability of forty anaesthetists to judge absolute levels of oxygen saturation, direction of change, and size of change in saturation using auditory pitch and pitch difference in two laboratory-based studies that compared a linear pitch scale with a logarithmic scale. In the former the differences in saturation become perceptually closer as the oxygenation level becomes higher whereas in the latter the pitch differences are perceptually equivalent across the whole range of values. ⋯ The line of best fit for the logarithmic function was also closer to x = y than for the linear function. The results of these studies can inform the development and standardisation of pulse oximetry tones in order to improve patient safety.